The Washington Redskins’ Terrelle Pryor sent a shock through the NFL on Wednesday when he charged that a fan in Kansas City repeatedly called him the N-word. Pryor exploded on fans after Washington’s Monday night game against the Kansas City Chiefs, and he cited the fan’s repeated racist terms as the reason.

The Kansas City Chiefs are saying they have not yet found evidence of the fan shouting at Pryor. But the team is not denying that the incident happened, and is encouraging fans to contact the team with information on this or any other racial or disruptive incident in the Arrowhead Stadium stands.

“Washington didn’t make our people aware of an incident, the people we have on the sideline didn’t see one before or after the game and as far as we know, no one from the league office was called to his aid during or after the game,” said Ted Crews, the Chiefs’ vice president of communications, according to a report in the Kansas City Star. “There was no incident or report from the stands.”

However, the Washington Post reported that several fans in the vicinity of Washington’s bench did indeed hear racial slurs being directed at the players. Two fans, who confirmed their attendance at the game via photos and ticket stubs, told the Post they heard a man in a Chiefs jersey shouting “[N-words] need to stand up for the anthem,” among other epithets. The fans indicated that the man did not appear to be targeting Pryor in particular, but that Pryor was the one who finally reacted.

Pryor claimed on Wednesday that a fan repeatedly called him the N-word, to the point that he had to bring over a member of NFL security. That was enough to draw the attention of the NFL, which promised to take a firm stance against any abusive or racist language.

“I don’t want to go too far down the road of hypotheticals, but we have no tolerance for racial remarks directed at anyone in a stadium,” NFL spokesman Joe Lockhart said. “Those fans are not welcome to come back this week, next week or any time. I don’t want to get ahead of the review, but our underlying principle is clear.”

Chiefs linebacker Derrick Johnson said he’s never heard the N-word at Arrowhead, though he has heard it at other stadiums on occasion. “I pray that didn’t happen, but if it did, shame on them,” Johnson told the Star. “I have a lot of respect for our fans, so I would hope that didn’t go on because that’s a bad reflection of what we are at Arrowhead.”